A time study engineer has studied the time taken to machine crank shafts. He has taken 40 observations and these are summarized in the form of frequency distribution as shown below:

Time (Minutes) Frequency 20 15 21 10 22 10 23 5 The performance rating of the operator machining the crank shaft is 110 per cent. Find the standard time for machining the crank shaft by assuming allowance of 15 per cent.

AppendixLO1